Field of the Invention
This invention relates generally to digital video displays, and more particularly to displays with features that improve latency.
Description of the Background Art
Liquid crystal displays typically include large arrays of individual pixels. Intensity values to be displayed by each pixel are typically represented by multi-bit data words, and each bit of the multi-bit data word is asserted on the pixel during a portion of a video frame time corresponding to the significance of the asserted bit. Each bit will cause the pixel to display either a light (“on”) or dark (“off”) intensity, depending on the values of the asserted bits. Over the frame time, an observer's eye integrates the light and dark intensities of the individual bits, to perceive an intermediate intensity value corresponding to the value of the multi-bit data word.
The process of loading each data bit onto each pixel takes some time. The latency of a display is defined as the amount of time between the receipt of a first portion of a frame of image data into a buffer of the display and the first assertion of data of that frame on the pixels of the display.
The increase in interactive display technology, such as computer monitors, video game consoles, and virtual reality headsets, among others, has created a need for systems with decreased latency. In such technology, video data must be altered as the user interacts with the device or with the world. For example, a head mounted display might display information over an object in the user's field of view. If the information is intended to be displayed in a fixed position with respect to the world, image data from the device must be constantly altered as the user moves his/her head or eyes with respect to the object. In known devices, visual artifacts (blurred or jerky object motion) are caused by the latency of the display device.
Efforts to improve latency in liquid crystal displays have not been fully satisfactory. While some have decreased latency in certain display devices, the delays remain significant in applications requiring immediate alteration of image data. For example, in known devices there is at least a one frame delay between receiving the image data and displaying it. What is needed, therefore, is a system and method for decreasing latency of a display to less than the frame time of the display.